A group of scientists has proposed a new theory about how Earth's atmosphere got its oxygen: The planet slowed down and days got longer.
一组科学家提出了一种关于地球大气如何获得氧气的新理论：地球(自转)速度变慢，白昼变长。
A recent study proposes that longer, continuous daylight caused bacteria to produce lots of oxygen.
最近的一项研究提出，连续不断的日照时间延长会促使细菌产生大量氧气。
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That oxygen made most of life as we know it possible.
氧气让我们所知的大部分生命得以存活。
The scientists dug up bad smelling, colorful bacteria from a deep sinkhole in Lake Huron, which is one of the Great Lakes in the northern United States.
科学家从休伦湖一处深坑中挖出了一些气味难闻，颜色艳丽的细菌，休伦湖是北美五大湖之一。
In laboratory experiments, the researchers gave the bacteria different amounts of light.
在实验室进行的实验中，研究人员用不同时长的光照照射细菌。
They found that the bacteria produce oxygen at a higher rate the longer they receive continuous light.
他们发现，这类细菌被连续照射的时间越久，产氧的速度就越快。
One of the great mysteries in science is how Earth went from a planet with little oxygen to the breathable air we have now.
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